The long-term goal of the proposed studies is to understand the influence of genetics on auditory function. The studies proposed will evaluate the impact of carrying recessive genes on auditory physiology by testing the hypothesis that carriers of genes for hearing loss themselves have auditory anomalies. We propose to study recessive hereditary hearing loss, both nonsyndromic and syndromic, in three groups with varying degrees of genetic isolation, namely the Acadian population of central Louisiana and a closely knit society of Orthodox Jewish Ashkenazi families. Acadian families and Orthodox Jewish Ashkenazi families with nonsyndromic recessive deafness will be studied, as well as Acadian families with Usher syndrome type I. Parents, sibling carriers, non-affected family members, and other control subjects will be evaluated using physiological measures of auditory function with emphasis on otoacoustic emissions (OAEs), considered a sensitive measure of cochlear function, and auditory evoked potentials, unmasking of auditory evoked potentials, and suppression of OAEs to assess peripheral auditory afferent and efferent neural function. Characterizing auditory physiologic function in distinct groups of individuals who carry genes for hearing loss will contribute to the basic understanding of the genetic mechanisms related to impaired auditory function and to understanding physiologic differences in auditory function in carriers of genes for hearing loss.